BSN Tracker

clarithromycin

Brand: Biaxin

⚠ BBW Prototype: azithromycin
Drug Class: macrolide antibiotic
Drug Family: antibiotic
Subclass: semisynthetic macrolide
Organ Systems: infectious-diseaserespiratorygastrointestinal

Mechanism of Action

Binds the 50S ribosomal subunit at the 23S rRNA, blocking peptide elongation and inhibiting translocation; bacteriostatic. Clarithromycin has enhanced activity against H. pylori and atypical organisms and is both an inhibitor and substrate of CYP3A4.

50S ribosomal subunit (23S rRNA)

Indications

  • community-acquired pneumonia (atypical)
  • acute exacerbations of chronic bronchitis
  • sinusitis
  • pharyngitis/tonsillitis
  • Helicobacter pylori eradication (triple or quadruple therapy)
  • MAC prophylaxis and treatment (in HIV)
  • skin and soft tissue infections

Contraindications

  • macrolide hypersensitivity
  • history of QTc prolongation or ventricular arrhythmia
  • concurrent use of colchicine in renal/hepatic impairment
  • ergotamine or dihydroergotamine (severe vasoconstriction)

Adverse Effects

Common

  • GI upset
  • diarrhea
  • nausea
  • abnormal taste (metallic)

Serious

  • QTc prolongation/torsades de pointes
  • hepatotoxicity
  • C. difficile colitis
  • serious drug interactions via CYP3A4 inhibition

Pharmacokinetics (ADME)

Absorption 55% oral bioavailability; food increases absorption of extended-release form
Distribution extensively distributed; high tissue concentrations
Metabolism hepatic CYP3A4 (also an inhibitor); active metabolite 14-hydroxyclarithromycin
Excretion hepatic (major) and renal; dose adjustment in severe renal impairment
Half-life 3–7 hours (parent); 5–9 hours (14-OH metabolite)
Onset rapid
Peak 2–3 hours
Duration 12 hours (IR) or 24 hours (XL)
Protein Binding 65–70%
Vd large

Drug Interactions

Drug / Agent Mechanism Severity
statins (simvastatin, lovastatin) CYP3A4 inhibition increases statin exposure; rhabdomyolysis risk major
colchicine inhibits CYP3A4 and P-gp, increasing colchicine to toxic levels; fatal toxicity reported major
warfarin CYP3A4 inhibition and gut flora suppression increase INR major
QTc-prolonging drugs additive QT prolongation; risk of torsades major

Nursing Considerations

  1. Always screen for interacting drugs before dispensing: colchicine, statins (simvastatin/lovastatin), warfarin, QTc-prolonging agents — these interactions can be life-threatening.
  2. Assess cardiac history; avoid in patients with known QTc prolongation, electrolyte abnormalities, or on other QTc-prolonging medications.
  3. Monitor INR in patients on warfarin; expect INR to rise during therapy and fall after completion.
  4. Advise patients of the characteristic metallic taste and GI side effects; taking with food may reduce GI upset.

Clinical Pearls

  • Clarithromycin is a potent inhibitor of CYP3A4, affecting the metabolism of a wide range of drugs; the prescriber must review for drug interactions before initiating therapy in any patient.
  • A black box warning exists for increased cardiovascular mortality in patients with coronary artery disease; azithromycin or doxycycline should be used as alternatives for atypical pneumonia in patients with CAD when possible.

Safety Profile

Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Required
TDM Not required
Guideline Update pending

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Acute Exacerbations Of Chronic Bronchitis Community-acquired Pneumonia (atypical) Helicobacter Pylori Eradication (triple Or Quadruple Therapy) MAC Prophylaxis And Treatment (in HIV) Macrolide Antibiotic Pharyngitis/tonsillitis Sinusitis Skin And Soft Tissue Infections
← Back to Medications